Open Cable standards define four channels: the Forward Application Transport (FAT) channel, National Television Standards Committee (NTSC) analog channel, Forward Data Channel (FDC), and the Reverse Data Channel (RDC). The FAT and NTSC analog signals are considered in-band signals, while the FDC and RDC are considered out-of-band. In Open Cable systems, a common cable carries both the FAT and FDC signals to a receiver, such as a set-top box, that extracts signals for communication to respective tuners. To separate the signals, the set-top box typically uses a directional coupler, which imparts a signal loss of approximately 1 decibel (dB) to the FAT signal and approximately 10 dB to the FDC signal.